Generally, representative methods to produce electricity include a thermal power generation method that uses fossil fuel as an energy source and a nuclear power generation method that uses nuclear fission.
However, thermal power generation has disadvantages of immense construction cost and environmental pollution attributable to combustion of fossil fuel. On the other hand, nuclear power generation is advantageous in terms of mass production of electricity but it poses many problems, including: immense cost for construction of facilities that can prevent leaking of radiation, strong resistance by local residents against construction of a new nuclear power plant because a nuclear power plant is recognized as an unpleasant facility, difficulties in treating radiative waste, and risk of destruction of the environment from even a minor accident.
Recently, attention has been made to using natural energy sources such as wind power, tidal power, hydroelectric power, or solar energy as an alternative energy to fossil fuel because they are clean energies that are free from risk of causing environmental pollution and are perpetual energy sources that are free from risk of exhaustion.
A hydroelectric power plant, which is the most commonly used type of power plant, does not directly cause environmental pollution. However, immense cost is incurred for construction of a dam, and dams may cause secondary environmental problems such as change of an ecosystem because a large area is submerged after construction of a dam. Further, large sized dames may even produce local weather changes.
On the other hand, wind power generation and solar energy generation have a problem of being dependent on weather conditions. That is, when there is no wind or sunlight, power generation is impossible.
Power generation technologies using clean energy have been developed. Therefore, various power generation methods using inexhaustible natural energy sources have been developed and become widely used. For example, there are many forms of power generation using energy sources obtained from the oceans, including sunlight, tidal current, temperature differences, wave power, tides, wind power, etc.
These power generation methods have an advantage of using clean energy which is free from risk of causing environmental pollution. However, these methods also have disadvantages. For example, tidal power generation is limitedly used due to geographical requirements. Therefore, it is difficult to apply tidal power generation universally. Furthermore, tidal power generation has problems of immense construction cost, devastation of foreshore, and negative influence on the environment of vast areas. Wave power generation and ocean thermal energy conversion (OTEC) also cannot be used universally because they can only be used in very limited locations.
Tidal current generation is given prominence as an alternative power generation method because it uses clean energy and due to the fact that it can perform continuous power generation regardless of weather conditions in an ocean environment. Tidal current generation is also limitedly used due to geographical location requirements but can be more broadly used than tidal power generation. Consequently, tidal current generation has been paid attention due to the fact that it actively uses kinetic energy of a tidal stream. However, it also has problems of installation of complex facilities and limited power generation capacity.
In order to solve the above problems, Korean Patent No. 10-1178482 discloses a “floating offshore combined power generation system.”
The floating offshore combined power generation system includes a floating body that floats on water, a photovoltaic power generator that is installed on the floating body and produces electricity using sunlight, a wave energy converter that is installed on the side of the floating body and produces electricity using the power of waves, a wind power generator that is installed on the floating body and produces electricity using the power of wind, and a tidal current generator that produces electricity using a tidal current that flows under the floating body. The floating offshore combined power generation system further includes a complex power management device that is electrically connected to the photovoltaic power generator, the wave energy converter, the wind power generator, and the tidal current generator to combine electrical energies generated by the power generators and controls the frequency and amplitude of the electrical energies generated by the power generators. The complex power management device includes a power controller that is electrically connected to the photovoltaic power generator, the wave energy converter, the wind power generator, and the tidal current generator and that controls the frequency and amplitude of electrical energies generated by the power generators by controlling the frequency and amplitude of an electric current generated by each power generator, a filter that eliminates a noise component in the electricity that is output from the power controller, and an interconnection controller that is connected to the filter and blocks an inverse voltage and a reverse current. The complex power management device combines electricity generated by each power generator into a single electric power source and supplies it as a commercial power source. The floating offshore combined power generation system is composed of a plurality of sectors that is electrically connected to each other. The floating offshore combined power generation system is controlled by an integrated management-and-control station that collectively controls electricity generated by each sector. The integrated management-and-control station includes an energy storage device that improves the quality of electricity dependent on variations in electricity generated by two or more kinds of generators and an interconnection controller that is installed between the energy storage device and the commercial power source and blocks an inverse voltage and a reverse current.
The conventional floating offshore power generation system having the structure and operation described above can maximize power generation capacity by continuously performing power generation using clean energies including sunlight, wave power, wind power, tidal current, etc. in ocean environment.
However, since the conventional floating offshore power generation system is composed of a plurality of power generators and its peripheral apparatuses are complicated mechanical parts, a fatal breakdown may occur upon occurrence of a water leak. Furthermore, the lifespan of the mechanical parts is inevitably shortened in extreme conditions of an ocean environment. That is, it is difficult to maintain the conventional floating offshore power generation system. In addition, it has a problem of low power generation efficiency per unit area.